Constructions for moisture sensitive thermochromic layers and structures having reduced moisture content in thermochromic layers

ABSTRACT

A stack or roll of alternating layers of films or sheets. The stack or roll includes an interlayer film or sheet with a thermochromic PVB of a polymer, at least one transition metal ion, at least one high epsilon ligand capable of forming a high epsilon metal-ligand complex with the transition metal ion and at least one low epsilon ligand capable of forming an low epsilon metal-ligand complex with the transition metal ion. A desiccant-containing film or sheet is juxtaposed or interleaved with the interlayer film or sheet. The desiccant-containing film or sheet prevents blocking of the interlayer film or sheet and is capable of removing moisture from the interlayer film or sheet. The desiccant-containing film or sheet is releasably attached to the interlayer film or sheet.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 12/816,635, filed Jun. 16, 2010, which in turn claimed thebenefit of U.S. Provisional Application Ser. No. 61/187,448 filed Jun.16, 2009. The entire contents of both of these applications are herebyincorporated by reference.

BACKGROUND

This disclosure relates to an improvement in moisture sensitive layersand in particular to polyvinyl butyral (PVB) film or sheet products andmore particularly to an improvement in the thermochromic PVB productsdescribed in the following commonly owned U.S. patents and applications:U.S. Pat. No. 7,538,931; U.S. Patent Publication No. 2008/0105851; U.S.Patent No. 7,525,717; and U.S. Pat. No. 7,542,196, all to Byker et al.and all of which are incorporated herein by reference. As described inthe '717 patent, thermochromic PVB products have a thermochromic layerthat includes a polymer, at least one transition metal ion, at least onehigh epsilon ligand capable of forming a high epsilon metal-ligandcomplex with the transition metal ion and at least one low epsilonligand capable of forming an low epsilon metal-ligand complex with thetransition metal ion. PVB is a copolymer sometimes designated aspoly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate). PVB is widelyused in making safety glass laminates for motor vehicle windshields andarchitectural safety glass.

Various film and layers including PVB films have a strong propensity toabsorb water. It is a common practice when manufacturing these films orsheets to maintain low relative humidity in the manufacturingenvironment and carefully package the rolls of film or sheet in moistureresistant packaging. Some of the thermochromic PVB films or sheetsdisclosed by Byker et al. are even more hygroscopic and more sensitiveto absorbed moisture and hence it is not uncommon to store rolls ofthermochromic PVB films or sheets under vacuum in the presence ofdesiccant. Moisture in the PVB films or sheets disclosed by Byker et al.is undesirable because it can decrease the performance of thethermochromic system in the films and the moisture can lead todeleterious reactions that decrease durability of the films.

SUMMARY

In accordance with this disclosure, moisture sensitive layers includingPVB films or sheets in general and PVB film or sheet products such asthe thermochromic film products mentioned above are assembled orjuxtaposed with a desiccant-containing film similar to those filmsand/or layers described in U.S. Patent Publication Nos. 2008/0185301,2008/0012172, 2007/0160789, 2006/0269708, 2004/0131805, and 2003/0235664to Merical, which are incorporated hereby by reference. It has beenfound that this construction reduces and/or maintains the amount ofmoisture in the films at low levels that in many instances enables thefilms to be laminated more easily with a reduced tendency to trapmoisture in the films or sheets when they are laminated between sheetsof glass.

In accordance with one manifestation of this disclosure, PVB films areassembled with a desiccant-containing film. In a further manifestationof the invention, the desiccant-containing film is removed prior tolamination of the PVB film. In a further manifestation of the invention,the thermochromic films described in the Byker et al. publishedapplications are assembled with a desiccant-containing film. In a stillfurther modification, the desiccant-containing film is removed from thethermochromic film prior to its lamination.

In accordance with another manifestation of this disclosure, thethermochromic film described above are supplied by interleaving thethermochromic films with a desiccant-containing film and thedesiccant-containing film is removed prior to laminating thethermochromic film to a panel of glass or between sheets of glass asdescribed in the aforementioned Published Applications to Byker et al.

In accordance with another manifestation of this disclosure, theinvention is a stack or roll of alternating layers of a moisturesensitive film or sheet and desiccant loaded, moisture absorbing film orsheet.

In accordance with another manifestation of this disclosure, theinvention is a stack or roll of alternating layers of a first polymericmaterial and a second polymeric material including or comprising amoisture absorbing desiccant.

In accordance with another manifestation of this disclosure, theinvention is a stack or roll of alternating layers of a first polymericmaterial and a second polymeric material including or comprising adesiccant.

In another manifestation of the invention the desiccant-containing filmis a polyethylene film having calcium oxide particles dispersed therein,and still more particularly, polyethylene film having calcium oxideparticles dispersed therein in the amounts and in the manner describedin the aforementioned Published Applications to Merical. In oneembodiment the polyethylene film having calcium oxide particlesdispersed therein is overcoated on one or both sides with moisturepermeable low density polyethylene which does not contain desiccant.This bilayer or trilayer construction of the interleaving film allowsfor moisture uptake by the desiccant-containing layer while minimizingor preventing contact between the desiccant and the moisture sensitivelayers including PVB film or sheet.

In one embodiment, a thermochromic film could be juxtaposed with adesiccant containing film, wound into a roll, stored and shipped, andthen unrolled, separated from the desiccant-containing film, and used bythe end user as otherwise described in the Byker et al. publications.

In still another embodiment, a plurality of thermochromic films could beinterleaved with a plurality of desiccant-containing films. The end userwould then remove the desiccant containing films and use thethermochromic film by, for example, laminating it between sheets ofglass appropriate for the end user's application.

While this disclosure specifically addresses PVB films, the teachingsherein may also be applicable to other films that are similar to PVB interms of their water absorbing character and sensitivity to the presenceof moisture. Other moisture sensitive films or sheets that form a firstlayer in an interleaved roll include fabrics, various types of paper,ethylene vinyl acetate, nylons and polyethylene terephthalate. Ofparticular interest is polyethylene terephthalate which has a tendencyto expand with moisture. Dimensionally stabilized polyethyleneterephthalate is very important for die cutting and circuit boardfabrication.

Layers and polymers beside polyethylene that can be used for a desiccantloaded second layer for interleaving include polypropylene, nylons,polyethylene terephthalate, PVB and ethylene vinyl acetate. Desiccatingmaterials other that calcium oxide that may be loaded into thedesiccating layer include magnesium oxide, calcium sulfate, magnesiumsulfate, silica, alumina and molecular sieves.

DETAILED DESCRIPTION

The following study was conducted to demonstrate proof of concept.

Procedure: Two thermochromic PVB films, one called blue type and onecalled orange type, were each cut into two pieces. One piece of eachtype that will be called “dry” was retained in a vacuum desiccator, andone of each type that was exposed to the relative humidity will becalled “wet.” The dry film of both the orange and blue film was cut intofive pieces. The wet film of both the orange and blue film was cut intofour pieces.

Dry film of both the orange and blue film

-   -   A. Cut A was left exposed to the ambient relative humidity, and        was tested every 24 hours for moisture content.    -   B. Cut B was left in the desiccator with a vacuum, and was        tested every 24 hours for moisture content.    -   C. Cut C was placed in a desiccating pouch labeled 24 hours, and        was tested for moisture content every 24 hours.    -   D. Cut D was placed in a desiccating pouch labeled 48 hours, and        was tested for moisture content after 48 hours of the pouch        being sealed. The pouch was resealed, and the film was tested        for moisture content every 24 hours after the initial 48 hours.    -   E. Cut E was placed in a desiccating pouch labeled 72 hours, and        was tested for moisture content after 72 hours of the pouch        being sealed. The pouch was resealed, and the film was tested        for moisture content every 24 hours after the initial 72 hours.

Wet film of both the orange and blue film

-   -   F. Cut F was left exposed to the ambient relative humidity, and        was tested every 24 hours for moisture content.    -   G. Cut G was placed in a desiccating pouch labeled 24 hours, and        was tested for moisture content every 24 hours.    -   H. Cut H was placed in a desiccating pouch labeled 48 hours, and        was tested for moisture content after 48 hours of the pouch        being sealed. The pouch was resealed, and the film was tested        for moisture content every 24 hours after the initial 48 hours.    -   I. Cut I was placed in a desiccating pouch labeled 72 hours, and        was tested for moisture content after 72 hours of the pouch        being sealed. The pouch was resealed, and the film was tested        for moisture content every 24 hours after the initial 72 hours.

In order to measure the low moisture contents in PVB film, a KarlFischer titration instrument was used. A sample of film in the KarlFischer instrument is heated and the water i.e. moisture in the film isswept into a solution by a flow of dry nitrogen gas. The solutioncontains methanol, imidazole, sulfur dioxide, and iodide ion. In acoulometric Karl Fischer titration, iodine is generated electrolyticallyat the anode. An oxidation/reduction reaction then occurs when sulfurdioxide reacts with iodine and the water in the sample as shown by:

I₂+SO₂+H₂O→2HI+SO₃   (1)

The iodine reacts with water in a one to one mole ratio, which allowsfor a direct relationship between the amount of electricity needed tocreate the iodine and the amount of water in the sample.

The pouches containing desiccant were made up of six layers. The firstfour, including an aluminum foil layer, are designed to keep moistureout of the pouch. Following these layers is a separator layer, which isfollowed by a peelable desiccant film that contains calcium oxide as thedesiccating material. The calcium oxide reacts with the moisture in theair in the bag, as shown in equation (2), and lowers the relativehumidity.

CaO+H₂O→Ca(OH)₂   (2)

Methods:

All Karl Fischer titration based moisture readings were performed usinga Mitsubishi Moisture Meter, CA-06 with a VA-06 Vaporizer. The oven wasset to 140° C., with a two minute purge, two minute heat up and twominute cool down before each sample. A 30000 μL capillary tube was usedat an oven temperature of 150° C. to calibrate the moisture meter beforeand after all the film tests were run, and was allowed to have a 5%margin of error. A small sample was cut from each of the pieces of film.The sample weighed between 0.2 and 0.25 grams.

The desiccating pouches were sealed with a thermal sealer with rollersand set to about 160° C. The pouches were then cut open to measure thefilm, and then resealed having been open for approximately five minuteseach time.

Results & Discussion:

In the analysis of the pouches, it is best to compare the control of thesame color film. All the data for the blue film are in Table 1, and allthe data for the orange film are in Table 2.

TABLE 1 Moisture percentage in the blue film using the Karl Fischertitration data. The indoor relative humidity, (RH), where the sampleswere stored and the outdoor RH are given on the days moisturemeasurements were made. Indoor RH = 48% RH = 45% RH = 50% RH = 49% RH =46% Outdoor RH = 87% RH = 67% RH = 72% RH = 78% RH = 60% SampleDescription 0 hours c.a. 24 hours c.a. 48 hours c.a. 72 hours c.a. 96hours A (Dry) open to air 0.33% 1.72% 1.744%  B (Dry) desiccator 0.33%0.16% 0.12% 0.22% 0.20% C (Dry) 24 hour pouch 0.33% 0.22% 0.23% 0.22%0.21% D (Dry) 48 hour pouch 0.33% 0.19% 0.16% 0.20% E (Dry) 72 hourpouch 0.33% 0.21% 0.21% F (Wet) open to air 1.79% 1.95% 1.78% 1.91%1.97% G (Wet) 24 hour pouch 1.79% 1.50% 1.31% 0.83% 0.71% H (Wet) 48hour pouch 1.79% 1.08% 1.01% 0.77% I (Wet) 72 hour pouch 1.79% 0.56%0.41%

TABLE 2 Moisture percentage in the orange film using the Karl Fischertitration data. The indoor relative humidity, (RH), where the sampleswere stored and the outdoor RH are given on the days moisturemeasurements were made. Indoor R = 48% RH = 45% RH = 50% RH = 9% RH = 6%Outdoor RH = 87% RH = 67% RH = 72% RH = 78% RH = 60% Sample Description0 hours c.a. 24 hours c.a. 48 hours c.a. 72 hours c.a. 96 hours A (Dry)open to air 0.19% 1.27% 1.30% B (Dry) desiccator 0.19% 0.13% 0.10% 0.20%0.14% C (Dry) 24 hour pouch 0.19% 0.16% 0.17% 0.20% 0.19% D (Dry) 48hour pouch 0.19% 0.17% 0.15% 0.18% E (Dry) 72 hour pouch 0.19% 0.12%0.16% F (Wet) open to air 1.37% 1.34% 1.21% 1.33% 1.34% G (Wet) 24 hourpouch 1.37% 0.98% 0.61% 0.39% 0.30% H (Wet) 48 hour pouch 1.37% 0.66%0.37% 0.27% I (Wet) 72 hour pouch 1.37% 0.25% 0.21%

The wet blue film started with 1.8% moisture content, and rose to asmuch as about 2.0% in open air. The moisture content of the blue filmthat had been placed in the 24 hour desiccant pouch was reduced by about0.3 percentage points. This continued to decline even when the pouch wasopened for testing and then resealed. The wet blue film in the 48 hourpouch was able to decrease the moisture content down to 1.01% comparedwith 1.31% in the 24 hour pouch, suggesting that opening the pouch didaffect its ability to remove moisture from the film, but did not ruinthe pouch. The wet blue film in the 72 hour pouch did the best after 96hours, by decreasing the moisture content of the film down to 0.41%, butall the pouches were able to decrease the moisture content below 0.8%after 96 hours as shown in Table 1.

The dry blue film started with 0.33% moisture content, and the vacuumdesiccator was able to further dry the film during the experiment to0.12%. As can be seen in Table 1, the moisture content of the blue filmbounces around. This could possibly be due to the fluctuation inrelative humidity, and the decreasing ability of the desiccant to do itsjob.

In comparison, the wet orange film in the pouches, which started withlower moisture content than the wet blue, were dried further than theblue. The wet orange film started with a moisture content of 1.37%, andafter 96 hours, the 72 hour pouch had dried the film to 0.21% indicatingthe rate of drying to be about 0.30 percentage points per day. Thedrying ability of the pouches is almost a linear relationship, as can beseen in Table 2. It also appeared that opening the pouch did affect itsability to dry the film, but not as drastically as with the blue film.

The dry orange film was also dried further by the pouches. The dryorange films, starting at 0.19% were dried to 0.14% in the vacuumdesiccator, and to an average of 0.18% in all three pouches. Thesevalues also varied as with the blue film.

In another experiment a moisture absorbing film was made up of a layerof low density polyethylene (“LDPE”), a layer of CaO loaded high densitypolyethylene (“HDPE”) and a layer of LDPE. An interleaved roll wasprepared with this material and a layer of PVB which contained 27 weight% tri(ethylene glycol) bis(2-ethylhexanoate) as plasticizer. Severalextra wraps of the desiccant loaded film were rolled onto the outersurface of the interleaved roll. This roll was stored unpackaged andotherwise unprotected indoors in a normal shop environment. At varioustimes during the storage, the roll was unrolled and samples of the PVBlayer were taken from the locations within the roll indicated in Table 3and analyzed for moisture content. The films were then re-rolled in theinterleaved configuration and stored for additional time. Thedesiccating interleave kept the PVB layers from sticking to each otherand thereby kept the roll from blocking The results of moisture testsare shown in Table 3. It is remarkable that the desiccating interleavelayer can remove moisture and extend the shelf life with regard tomoisture content of the PVB even when the interleaved roll is storedunpackaged in an open shop environment.

TABLE 3 Weight Percent Moisture in PVB Film as determined by KarlFischer Titration for Interleaved Roll with Alternating Layers of theDesiccating Layer and Plasticized PVB Layer. inner most film ⅔ of the ⅓of the Hours on core way in way in outer most film 0 0.60% 0.58% 0.56%0.61% 24 0.55% 0.52% 0.47% 0.46% 168 0.37% 0.43% 0.38% 0.32% 336 0.29%0.28% 0.28% 0.30% 672 0.11% 0.13% 0.09% 0.37%

Similar experiments have been conducted with rolls of thermochromic PVB.In these experiments the moisture content in the thermochromic PVB isdecreased by storage with a desiccating interleave layer. Commerciallyavailable examples of desiccating CaO filled interleave layers areDM-8977 and DZ-3458 available from Alcan Packaging of Marshall, N.C. Thepreferred thicknesses of the desiccating interleave is 0.001 inches to0.01 inches. In one embodiment, the thickness for the trilayer ofLDPE-CaO loaded HDPE-LDPE is 0.0025 inches prior to any optionalsupport. These co-extrude calcium oxide loaded polyethylene trilayersfrom Alcan were embossed by passage between a rubber nip roll and steelemboss roll with a female emboss pattern 0.012″ to 0.013″ deep.Embossing took place with emboss roll temperature of 95° C., a nippressure of 150 pounds per linear inch and a line speed of 3 feet perminute.

In one embodiment, after a roll was formed with the moisture sensitivethermochromic PVB and the desiccating interleave, additional protectionfrom moisture ingress into the PVB was provided by placing theinterleaved roll in a metal foil lined bag and sealing the bag.Alternately, in another embodiment, the roll was protected by wrappingthe roll with an external film. The external film was about 1 to 20extra wraps of desiccating interleave that sacrificially preventsmoisture from getting to the rest of the roll. Even when part of theroll is removed and the PVB is used to make laminates, a low moisturecontent can be maintained and shelf life extended for the rest of theroll by repackaging and subsequent storage with the remainingdesiccating interleave. The thermochromic performance in the PVB wasincreased by the removal of moisture by the desiccating interleave. Thelongevity predicted by accelerated durability in a xenon arc lightexposure chamber also increased. Also, the desiccating interleave keptthe thermochromic PVB layers from sticking to each other and therebykept the roll from blocking

When PVB is used as an interlayer between two pieces of glass to make asheet of laminated safety glass, it is preferred that the PVB have roughtextured outer surfaces. The surface should be sufficiently roughlytextured to allow air to be expelled from the glass/PVB/glass threelayer stack when the stack is passed through a heated pinch roller totack the film to the glass sheets and create an edge seal for laterautoclave processing. The textured outer surface on the PVB can beinduced by surface melt fracture or by embossing the PVB layer on one orboth sides. It has been discovered that when PVB with a textured outersurface is interleaved with a desiccating layer with smooth surfaces thesurface texture of the PVB is lost while setting on the interleavedroll. However it has also been discovered that when the desiccatinglayer is also textured it can be used as an interleaving layer for PVBwith minimal negative impact on the PVB surface texture. In oneembodiment, adequate texture can be provided on the desiccating layer byseparately embossing the desiccating layer between a rubber nip roll andsteel emboss roll. Preferred conditions are a emboss roll temperature of95° C., a nip pressure 150 pounds per linear inch and a line speed of 3feet per minute.

In one embodiment, a desiccating layer was made up of co-extruded layersof LDPE, a layer of CaO filled HDPE and a layer of LDPE. This trilayerhad the appearance of a single film. In one instance, an interleave wasprepared with this desiccant loaded film and a layer of PVB whichcontained 27 weight % tri(ethylene glycol) bis(2-ethylhexanoate) asplasticizer. After several weeks the roll with alternating layers of thedesiccating layer and the plasticized PVB layer was unrolled and it wasdiscovered that the desiccating layer had wrinkled, giving the layer a“worm eaten wood” appearance. The wrinkling of the desiccating layertransferred into the PVB layer and made it difficult to use the PVB tolaminate together pieces of glass. The wrinkles caused opticaldistortion, void area and/or bubbles to appear in the laminate of twopieces of glass with this PVB interlayer. But, when this samedesiccating layer is first bonded to a permeable support like a nonwovenfabric or mesh and then interleaved with PVB to make a roll ofalternating layers of the desiccating layer and the plasticized PVBlayer the wrinkling problem can be eliminated or significantly reduced.When such a roll was stored for a month and unrolled, it was essentiallyfree of wrinkles and buckling in the PVB layer and the PVB layer wasused to make laminates with two sheets of glass with the PVB as aninterlayer. These laminates were free of optical distortion, void areaand bubbles.

One example of nonwoven is a polyethylene nonwoven available under thetrade name CLAF®, from Atlanta Nisseki CLAF, Incorporated. One or morethan one layer of nonwoven can be used as a support for the desiccatinginterleave layer. The nonwoven not only provides support for thedesiccating interleave to minimize wrinkling, it provides surfacetexture on the desiccating interleave that minimizes the loss of texturefrom the PVB that is interleaved with the desiccating film. The nonwovenalso helps prevent sticking of the layers of film to each other.

In summary, one manifestation of the invention is a film constructioncomprising a layer of PVB and a layer of a desiccant-containing film.

Another manifestation of this disclosure is a stack or roll ofalternating layers of a moisture sensitive film or sheet and desiccantloaded, moisture absorbing film or sheet.

Another manifestation of this disclosure is a stack or roll ofalternating layers of a first polymeric material and a second polymericmaterial including a moisture absorbing desiccant.

Another manifestation of this disclosure is a stack or roll ofalternating layers of a first polymeric material and a second polymericmaterial including a desiccant.

Another manifestation is the aforementioned construction packaged orwrapped in an external film that cooperates with thedesiccant-containing film to provide a PVB film exhibiting reducedmoisture content.

In another manifestation, a construction comprising a layer or sheet ofPVB and the layer of the desiccant-containing film is wound into a roll.

In another manifestation, the desiccant-containing film is texturedprior to being wound with PVB into a roll and helps preserve texture onthe PVB it is interleaved with.

In another manifestation, the desiccant-containing film is supported bya nonwoven mesh prior to being wound into a roll with a film of PVB andminimizes wrinkle formation in the films during storage.

In a further manifestation, the layers of the film construction arearranged such that when wound into a roll, one or more wraps of thedesiccant-containing film resides on the outer surface of the roll.

In a further manifestation of the invention, a method of providing a PVBfilm or construction having reduced moisture is provided which comprisesproviding a PVB film, and placing the PVB film between adjacent layersor windings of a desiccant-containing film.

A further manifestation of the invention is a thermochromic producthaving any of the constructions described in the Byker et al.publications wherein the thermochromic product is placed betweenadjacent films or windings of a desiccant-containing film.

In a more particular manifestation of the invention, thedesiccant-containing film is a film including a polymer and a desiccantwherein the polymer and desiccant are any of the materials described inthe Merical publications.

In a still more particular manifestation of the invention, thedesiccant-containing film comprises polyethylene and calcium oxideparticles.

In a still more specific manifestation of the invention, thedesiccant-containing film is a polyethylene film having calcium oxideparticles dispersed therein which is overcoated on one or both sideswith a moisture-permeable low density polyethylene.

Having described the invention in detail and with reference to specificembodiments thereof, it will be apparent that numerous variations andmodifications are possible without departing from the spirit and scopeof the following claims.

Having described the invention in detail and by reference to specificembodiments thereof it will be apparent that numerous variations andmodifications are possible without departing from the spirit and scopeof the following claims.

What is claimed is:
 1. A stack or roll of alternating layers of films orsheets comprising: an interlayer film or sheet comprising athermochromic PVB, wherein the thermochromic PVB comprises a polymer, atleast one transition metal ion, at least one high epsilon ligand capableof forming a high epsilon metal-ligand complex with the transition metalion and at least one low epsilon ligand capable of forming an lowepsilon metal-ligand complex with the transition metal ion; and adesiccant-containing film or sheet juxtaposed or interleaved with theinterlayer film or sheet; wherein the desiccant-containing film or sheetprevents blocking of the interlayer film or sheet; wherein thedesiccant-containing film or sheet is capable of removing moisture fromthe interlayer film or sheet; and wherein the desiccant-containing filmor sheet is releasably attached to the interlayer film or sheet.
 2. Thestack or roll of claim 1 wherein the desiccant-containing film or sheetinterleaves the interlayer film or sheet.
 3. The stack or roll of claim1 wherein the desiccant-containing film or sheet has a textured surfaceor is bonded to a support that has a textured surface.
 4. The stack orroll of claim 3 wherein the desiccant-containing film or sheet isembossed to provide the textured surface.
 5. The stack or roll of claim3 wherein the desiccant-containing film or sheet is bonded to one ormore than one permeable support layer.
 6. The stack or roll of claim 3wherein the desiccant-containing film or sheet is bonded to one or morethan one layer of mesh or fabric.
 7. The stack or roll of claim 3wherein the desiccant-containing film or sheet is bonded to one or morethan one layer of nonwoven.
 8. The stack or roll of claim 7 wherein thedesiccant-containing film or sheet is bonded to one or more than onelayer of polyethylene nonwoven.
 9. The stack or roll of claim 1 whereinthe stack or roll is packaged or wrapped in an external film thatcooperates with the desiccant-containing film or sheet to provide athermochromic PVB film or sheet exhibiting reduced moisture.
 10. Thestack or roll of claim 1 comprising the interlayer film and thedesiccant-containing film wound into a roll.
 11. The stack or roll ofclaim 10 wherein the desiccant-containing film resides on the outersurface of the roll.
 12. The stack or roll of claim 1 wherein thedesiccant-containing film or sheet comprises polyethylene and calciumoxide particles.
 13. The stack or roll of claim 12 wherein thedesiccant-containing film is a polyethylene film having calcium oxideparticles dispersed therein which is overcoated on one or both sideswith a moisture-permeable low density polyethylene.
 14. The stack orroll of claim 1 wherein the interlayer film or sheet and thedesiccant-containing film or sheet are both textured, wherein thetexture of the desiccant-containing film or sheet helps preserve thetexture of the interlayer film or sheet.
 15. The stack or roll of claim1 comprising a sealed bag with a foil lining therein, wherein the sealedbag contains the stack or roll of the interlayer film or sheet and thedesiccant-containing film or sheet.
 16. The stack or roll of claim 1wherein the moisture content of the interlayer film or sheet is belowabout 0.4%.
 17. The stack or roll of claim 1 wherein the wherein thedesiccant-containing film or sheet has a thickness from 0.001 inches to0.01 inches.
 18. A stack or roll of alternating layers of films orsheets comprising: an interlayer film or sheet comprising athermochromic PVB, wherein the thermochromic PVB comprises a polymer, atleast one transition metal ion, at least one high epsilon ligand capableof forming a high epsilon metal-ligand complex with the transition metalion and at least one low epsilon ligand capable of forming an lowepsilon metal-ligand complex with the transition metal ion; and adesiccant-containing film or sheet juxtaposed or interleaved with theinterlayer film or sheet; wherein the desiccant-containing film or sheethas a textured surface or is bonded to a support that has a texturedsurface. wherein the desiccant-containing film or sheet preventsblocking of the interlayer film or sheet; wherein thedesiccant-containing film or sheet is capable of removing moisture fromthe interlayer film or sheet; and wherein the desiccant-containing filmor sheet is releasably attached to the interlayer film or sheet.
 19. Astack or roll of alternating layers of films or sheets comprising: aninterlayer film or sheet comprising a thermochromic PVB, wherein thethermochromic PVB comprises a polymer, at least one transition metalion, at least one high epsilon ligand capable of forming a high epsilonmetal-ligand complex with the transition metal ion and at least one lowepsilon ligand capable of forming an low epsilon metal-ligand complexwith the transition metal ion; wherein the interlayer film or sheet hasa textured surface; and a desiccant-containing film or sheet juxtaposedor interleaved with the interlayer film or sheet; wherein thedesiccant-containing film or sheet has a textured surface or is bondedto a support that has a textured surface. wherein thedesiccant-containing film or sheet is capable of removing moisture fromthe interlayer film or sheet; and wherein the textured surface of thedesiccant-containing film or sheet or the support is releasably attachedto the textured surface of the interlayer film or sheet.
 20. The stackor roll of claim 19 wherein the desiccant-containing film or sheetprevents blocking of the interlayer film or sheet.